The present invention relates generally to electrical switching apparatus, and more particularly to an improved multiposition rotary switch for interconnecting different electrical contact pads on an insulating substrate such as a printed circuit board.
Modern electronic equipment makes substantial use of so-called "printed" circuitry, and it is often necessary or desirable to perform multiple switching operations directly on the board or other substrate bearing the circuitry. A number of different multiposition rotary switch constructions have been proposed for such use. Certain constructions, such as those disclosed in U.S. Pat. Nos. 3,031,541 to Hoffmann and 3,531,603 to Ashman, include a rotor having bridging contact means for interconnecting fixed contact pads arranged in concentric rings on a printed circuit board. The contact means bridge corresponding pads in the different rings at appropriate angular positions of the rotor.
While satisfactory in many applications, such prior art designs have a number of drawbacks. For example, rotor contacts of the type shown in Ashman are relatively bulky, making them unsuited for use in miniature switches, particularly in applications requiring a large number, e.g., 20 or more, switch positions. Moreover, the use of a separate coil spring in each contact assembly to produce the necessary contact force increases both the cost and the complexity of the switch. The integral detent cam/contact carrier construction of Hoffmann limits design flexibility and greatly increases the overall size of multirotor-type switches.
Accordingly, one object of the present invention is to provide an improved multiposition rotary switch adapted for circuit board use which is without the drawbacks of known prior art designs.
Another object of the invention is to provide an extremely compact multiposition rotary switch which can be manufactured economically in large quantity.
Yet another object of the invention is to provide an improved rotary switch construction employing modular elements which can be assembled in different combinations for different applications.
Still another object of the invention is to provide an improved rotatable bridging contact-type printed circuit switch having a rotor adapted for mounting multifinger wipers in different operational orientations.
Some electronic instruments, some cathode ray oscilloscopes for example, require a multiple section rotary switch having plural operating modes, including one mode in which the rotors of the different sections are coupled together for simultaneous rotation, and another mode in which they are independently rotatable. Certain of these instruments require a switch of the type just described in which the independent rotation mode is selectable only at certain switch positions, or in which a given section's rotors are independently rotatable only within a range of switch postions determined by the position of another section's rotors.
In prior art printed circuit rotary switches, coupling and decoupling of different switch sections is accomplished by means in the switches' operating knobs. Knobs including releasable coupling mechanisms are necessarily much larger than desirable in many applications, particularly those where instrument panel space is limited. Thus there is a need for a compact releasable coupler able to perform the above-described functions, and capable of being integrated into a miniature printed circuit rotary switch.
Accordingly, a further general object of the invention is to provide an improved releasable coupler mechanism constructed to meet the just-described needs in a practical and satisfactory manner.
A related object is to provide an improved multiple section, shaft operated rotary switch having integrated means releasably coupling the sections together for conjoint operation, and having operating shaft-actuated means for decoupling the sections to enable independent operation.
A more specific object of the invention is to provide a compact, integrated, inter-section coupler for a multiple section, shaft-operated rotary switch, the coupler being releasable upon axial movement of one section's operating shaft to enable independent operation of that section.
Still a further object of the invention is to provide such a coupler having means preventing its release in certain switch positions.
Yet a further object of the invention is to provide a coupler of the type described in which the switch position setting of one section determines the range of positions within which another section can be operated independently.
These and other objects, features and advantages of the present invention will be apparent to those skilled in the art as the following detailed description of certain preferred embodiments is read in conjunction with the accompanying drawings.